Bottom Anti-Reflective Coatings Understanding Brewer...

Brewer Science Inc., Rolla MO, USAEffective Date: 0X/0X/02 DCIF: MKT00XX Doc. Control#: F.6.6.010X.A

Understanding Brewer Science’s

Bottom Anti-Reflective Coatings


Overview

• Anti-reflective coating introduction

• Types of anti-reflective coating

• Advantages to anti-reflective coatings

• Advantages to bottom anti-reflective coatings

• Guide to products and compatibility


Substrate

ARC

ExposureEnergy

Anti-Reflective Coating Introduction

• Anti-reflective coatings (ARC) can do several things– Absorb light entering the material by light absorbing compounds in material.

– If ARC is the correct thickness can cause destructive interference of reflected light.


Types of Anti-reflective Coatings

• Organic– Applied like a photoresist

– Top anti-reflective coating (TARC)

– Applied after the photoresist

– Absorbs light to give little reflection at substrate/resist surface

– Bottom anti-reflective coating (BARC)

– Applied before the photoresist

– Absorbs light and uses destructive interference to give little reflection at theresist/ARC interface

• Inorganic– Deposited on substrate in special deposition chamber


Property Organic ARC Inorganic ARCReflectivity and swing ratioreduction - 1st minimum

++ +++

Reflectivity and swing ratioreduction - 2nd and higher minima

+++ 0

Etch rate 0 or + +++Coating conformity 0 ++Thickness tolerance + 0Plasma damage +++ --Refr. index reproducibility +++ 0Throughput ++ +Cost of Ownership + 0Stack issues +++ -Planarization capability ++ --Rework capability +++ --

Organic and Inorganic ARC


Advantages of Anti-Reflective Coatings

• Eliminates swing effect and standing waves in

photoresist

• Solves topography related lithography problems

• Provides ultimate critical dimension (CD)

control

• Expands process capabilities.


Exposure Energy Exposure Energy

Standing Wave

Reflective Notching

Resist

ResistARC®

Topography Related Lithography Problems

• Light reflecting off underlying substrate reduced or eliminated– Backscattering

– Reflective notching

– Standing Waves


Light Light

Unexposedphotoresist

MetalLine

Reflective Notching

Metalline

Photoresist

CrossSection

Reflective Notching


0.4µm on 2500Å steps using 1844Å XHRi

Competitor BARC

Reflective Notching


Dose to Clear Swing

Resist Thickn ess (nm)

Dos

e (m

J)

5 0

5 5

6 0

6 5

7 0

7 5

8 0

8 5

9 0

9 5

100

850 900 950 1000 1050

No ARC

XHRi

Swing Effects• Dose to clear swing curve defined as the amount of light required

to completely expose photoresist

• Swing curves reduced with application of BARC


0 .00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0

ARC®Thickness

AluminumGaAsPolyTungsten

BARC Reflectivity Curve


0.4µm with 2500Å Steps with 1844Å ARC XHRi

High Area

Transition Flat Area

Low Area

Resist Profiles on Topography


Advantages of organic BARC

• Can apply with existing photoresist application systems

• Do not need expensive deposition chambers

• Prevents chemical interaction between photoresist and substrate– BARC acts as wall to nitrogen poisoning with chemically amplified photoresists

• Increases CD control– Eliminates reflective notching

– Eliminates standing waves and scattered light

• Extends lithography process window– Increases stepper focus latitude

– Maximizes photoresist exposure latitude

– Increases usage life of stepper.


0

200

400

600

800

1000

1200

1400

1600

1800

2000

1000 1500 2000 2500 3000 3500 4000 4500 5000

Spin Speed (RPM)

DUV42-6DUV42-8DUV42-11

Example Spin Speed Curve


PEK-103 0.20µm L/S Resist on DUV42

Lines With or Without BARC


Guide to BSI BARC’s

• Exposure wavelength– G-line, I-line, DUV, 193nm

• Planar or conformal BARC– Worst case step height

– CD tolerances needed

• Wet or dry processing– Depending on equipment availability, CD and wavelength

– Wet process BARC develops away with resist

– Dry process BARC requires a gas etcher

• Choose BARC based on resist chosen– DUV resists have two chemistries

– ACETAL

– ESCAP/TBOC


PLANAR BARC

RESIST RESIST RESIST RESIST

CONFORMAL

BARC

EQUALRESIST

THICKNESS THINRESIST

EQUIVALENTBARC

THICKNESS

SUBSTRATE SUBSTRATE

Planar vs Conformal BARC


InorganicDeveloper Insoluble

OrganicDeveloper Insoluble

OrganicDeveloper Soluble

Exposure

Development

Etch

Stripping

SubstrateAnti-reflectiveBottom coat Photoresist

Wet or Dry Etch Processing


Bake Latitude

CD

Bake Temperature

Stable Lines Spaces Clear

MissingPattern

SpaceResidue

Stepper & Resist Resolution Limit

What is a Bake Window?


0.35 µm Dense Lines

177°C Bake 205°C Bake

Wet or Dry Etch Patterning


Planar BARC gives superior photo performanceConformal BARC gives superior etch performance

Various viscosities available in each family

BSI BARC Product Families

• G-line (broadband material)– Wet or dry process

– XLT– XLX

• I-line– Wet or dry process

– WiDE– Dry process only

– XHRi– XHRiA

• DUV– Dry Process Only

– ESCAP/TBOC compatable– DUV30 (planar)– DUV42 (conformal)

– ACETAL compatable– DUV32 (planar)– DUV44 (conformal)


Etch Capabilities

• Successfully dry etched in various chemistries

– HBr

– O2

– Cl2, HCl

– CF4, C2F2

– N2

– Carrier gases: He, Ar


After HBr/O2 etch.∆CD = 0.026µm.Selectivity = 0.85

After He/O2 etch.∆CD = 0.024µm.Selectivity = 1.04

After Cl2/O2 etch.∆CD = 0.013µm.Selectivity = 1.48

DUV42 Etch Performance


Cleaning/Stripping Capability

• BARC can be removed by common photoresiststripping processes

– Oxidizing plasma or oxidizing solvent strip processes

– Ozone Plasma Strip

– O2 Plasma

– Piranha

– RCA Clean

Date post:	17-Aug-2020
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